Assessing the response of plant flavonoids to UV radiation: an overview of appropriate techniques

Abstract

Flavonoids are a large group of plant secondary metabolites that are present in most plants, and are vital for plant growth, development and protection. Among the many functions of these compounds is their contribution to stress amelioration. The accurate identification and quantification of total or individual flavonoids in plants exposed to stressful conditions (e.g. ultraviolet radiation) is challenging due to their structural diversity. The present review provides the up to date knowledge and highlights trends in plant flavonoid analysis. The review covers all steps from the field to the laboratory, focussing on UV-B effects on flavonoids, and identifying critical issues concerning sample collection, pre-treatment, and extraction techniques and quantitative or qualitative analysis. A well-planned sampling and sample prehandling strategy is vital when capturing organ, tissue and developmentalstage dependent changes in flavonoids, as well as the dynamic changes due to time of UV-exposure and diurnal or seasonal parameters. A range of advanced extraction and purification techniques can facilitate the quantitative recovery transfer of flavonoids to solvents. The advantages and disadvantages of analytical methods, including chromogenic assays, liquid and thin-layer chromatography, mass spectrometry, NMR detection, and non-destructive in situ fluorescent analysis need to be consciously evaluated in the context of the specific biological question posed. Thus, no one method can be applied to every single study of flavonoid. The message of this review is that researchers will need to carefully consider the biological process that they intend to study, and select an analytical method that optimally matches their specific objectives.

Optimization of Aqueous Extraction from Kalanchoe pinnata Leaves to Obtain the Highest Content of an Anti‐inflammatory Flavonoid using a Response Surface Model

“…Furthermore, freeze and freeze‐drying can be considered important steps for a large‐scale and a controlled production of plant‐based products (Araújo and Bauab, ). Both are common procedures to avoid flavonoid degradation in plant materials, mainly when the extraction of the fresh samples is not possible (Julkunen‐Tiitto et al ., ).…”

Multicolor Fluorescence Imaging as a Candidate for Disease Detection in Plant Phenotyping

“…Currently, the use of this technique on proximal sensing is limited to the use of few available devices (Cerovic et al, 2012; Latouche et al, 2015). These devices have proved useful in the assessment of flavonoids content in grapes or kiwifruit, and in the detection of the nitrogen status for several species (Julkunen-Tiitto et al, 2014). However, the devices available up to date are not imaging sensors, which limits their applicability in field measurements and plant phenotyping programs.…”

Effects of Salinity Stress on Growth and Phenolics of Rice (<i>Oryza sativa</i> L.)

“…Phenolic compounds, a group of secondary metabolites, have different biological activities, and the most important capability is antioxidant activities [13,14]. Additionally, these compounds are accumulated to response in the increases of ROS under salt stress [15,16,17] by exhibiting antioxidant activity in tissues to inactivate lipid free radicals or prevent decomposition of hydroperoxides into free radicals [18,19,20]. Higher buildup of phenolics and flavonoids in the plant under salt stress may assist the plant to lighten the salinity-induced oxidative stress [21].…”